Audi TT 03 60k 1.8t 225 large radiator fan not working

[Fixanything]

Small fan works when ac turned on
Big fan or small fan do not operate when coolant temp gets above 100C either fast or slow speed.

Don,t want get in the mode of changing everything, appriciate any diagnostic tricks to narrow down faulty component eg fan/s, thermal fan switch, fan control module, (fuzes are OK), note: I have changed both the thermostat (fixed never getting above 70C) and coolant temperature sensor (fixed ECU reporting engine temp sensor fault code) with genuine parts, the big fan not working is new. Note: engine does not overheat during normal use however, if belt along on motorway for a hour then immediatley get stuck in traffic for 20mins it does 110C and you notice the big fan is not operating ! as you move again temp drops and is all good, never any coolant loss or boiling over.

Thanks Mark T

[SuperchargedVR6]

Sounds like the fan control module. VR6s, R32s, 1.8Ts all use a very similar box and was quite a common problem.

You could try bridging the relevant connections to confirm first:-

http://www.google.co.uk/url?sa=i&rct=j&q=&...

[Fixanything]

Vr6

Thanks for quick reply, initial look at the fan/s circuit diagram and control module pin outs (thanks very helpful) both the small and large fans are wired in parallel, so if 1 fan is ON the other fan should be ON either slow or fast speed but they are not both running, indicating a faulty fan or associated wiring to the fan. Eg when ac turned on both fans should turn as they are both connected to the same input supply 12volt wire and both have a common earth. Make sense ?

Cheers
Mark t

[Gren]

Exact thing happened to me. Mk1 225 at around 65k and 6 years old. Fine when moving but if sat in traffic for more than a couple of minutes it crept up. I ran it for a month or so like that while I got it diagnosed and sorted.

Ended up having a new fan fitted. Been a few years now so can't remember the exact details.